Rotational atherectomy device

ABSTRACT

An elongate tubular body extends between a rotatable cutter tip and a control. The cutter tip is connected to the control with a rotatable element. The control has an indicator which reveals resistance to rotation of either the rotatable element or cutter tip. Material which has been processed by the cutter tip is aspirated through the tubular body for disposal.

BACKGROUND OF THE INVENTION

This invention relates to medical devices and particularly to arotational atherectomy catheter device.

A variety of techniques and instruments have been developed for use inthe removal or repair of obstructive material in arteries and other bodypassageways. A frequent objective of such techniques and instruments isthe removal of atherosclerotic plaques in a patient's arteries.Atherosclerosis is characterized by the buildup of fatty deposits(atheromas) in the intimal layer (under the endothelium of a patient'sblood vessels). Over time, what initially is deposited as relativelysoft cholesterol-rich atheromatous material often hardens into acalcified atherosclerotic plaque. Such atheromas are often referred toas stenotic lesions or stenoses, the blocking material being referred toas stenotic material. If left untreated, such stenoses can sosufficiently reduce perfusion that angina, hypertension, myocardialinfarction, strokes and the like may result.

Several kinds of atherectomy devices have been developed for attemptingto remove some or all of such stenotic material. In one type of device,such as that shown in U.S. Pat. No. 5,092,873 (Simpson), a cylindricalhousing, carried at the distal end of a catheter, has a portion of itsside-wall cut out to form a window into which the atherosclerotic plaquecan protrude when the device is positioned next to the plaque. Anatherectomy blade, disposed within the housing, is then advanced thelength of the housing to lance the portion of the atherosclerotic plaquethat extends into the housing cavity. While such devices provide fordirectional control in selection of tissue to be excised, the length ofthe portion excised at each pass of the atherectomy blade is necessarilylimited to the length of the cavity in the device. The length andrelative rigidity of the housing limits the maneuverability andtherefore also limits the utility of the device in narrow and tortuousarteries such as coronary arteries. Such devices are also generallylimited to lateral cutting relative to the longitudinal axis of thedevice.

Another approach which solves some of the problems relating to removalof atherosclerotic plaque in narrow and tortuous passageways involvesthe use of an abrading device carried at the distal end of a flexibledrive shaft. Examples of such devices are illustrated in U.S. Pat. Nos.4,990,134 (Auth) and 5,314,438 (Shturman). In the Auth device, abrasivematerial such as diamond grit (diamond particles or dust) is depositedon a rotating burr carried at the distal end of a flexible drive shaft.In the Shturman device, a thin layer of abrasive particles is bondeddirectly to the wire turns of an enlarged diameter segment of the driveshaft. The abrading device in such systems is rotated at speeds up to200,000 rpm or more, which, depending on the diameter of the abradingdevice utilized, can provide surface speeds of the abrasive particles inthe range of 40 ft/sec. According to Auth, at surface speeds below 40ft/sec his abrasive burr will remove hardened atherosclerotic materialsbut will not damage normal elastic soft tissue of the vessel wall. See,e.g., U.S. Pat. No. 4,990,134 at col. 3, lines 20-23.

However, not all atherosclerotic plaques are hardened, calcifiedatherosclerotic plaques. Moreover, the mechanical properties of softplaques are very often quite close to the mechanical properties of thesoft wall of the vessel. Thus, one cannot always rely entirely on thedifferential cutting properties of such abrasives to removeatherosclerotic material from an arterial wall, particularly where oneis attempting to entirely remove all or almost all of theatherosclerotic material.

Moreover, a majority of atherosclerotic lesions are asymmetrical (i.e.,the atherosclerotic plaque is thicker on one side of the artery than onthe other). Since the stenotic material will be entirely removed on thethinner side of an eccentric lesion before it will be removed on theother, thicker side of the lesion, during removal of the remainingthicker portion of the atherosclerotic plaque the abrasive burr of theAuth device or the abrasive-coated enlarged diameter segment of thedrive shaft of the Shturman device necessarily will be engaging healthytissue on the side which has been cleared. Indeed, lateral pressure bysuch healthy tissue against the abrading device is required to keep theabrading device in contact with the remaining stenotic tissue on theopposite wall of the passageway. For stenotic lesions that are entirelyon one side of an artery (a relatively frequent condition), this meansthat the healthy tissue across from the stenotic lesion will be exposedto and in contact with the abrading device for substantially the entireprocedure. Moreover, pressure from that healthy tissue against theabrading device will be, in fact, the only pressure urging the abradingdevice against the atherosclerotic plaque. Under these conditions, acertain amount of damage to the healthy tissue is almost unavoidable,even though undesirable, and there is a clear risk of perforation orproliferative healing response. In some cases, this "healthy tissue"across from a stenotic lesion may itself be somewhat hardened (i.e., ithas diminished elasticity); under such circumstances, the differentialcutting phenomenon described by Auth will also be diminished, resultingin a risk that this "healthy" tissue may also be removed, potentiallycausing perforation.

Thus, notwithstanding the foregoing and other efforts to design arotational atherectomy device, there remains a need for such a devicewhich can advance through soft atheromas while providing minimal risk tothe surrounding vessel wall. Preferably, the device also minimizes therisk of dislodging emboli, and provides the clinician with real-timefeedback concerning the progress of the procedure.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a rotationalmedical device is provided having an elongate flexible tubular body. Thetubular body has a proximal end and a distal end. The tubular body alsohas a rotatable element which extends throughout its length. At thedistal end of the tubular body is a rotatable cutter tip which isconnected to the rotatable element. At the proximal end of the tubularbody is a control having an indicator which indicates the resistance torotation of either the cutter tip or the rotatable element. Preferably,the tubular body is provided with a vacuum coupling to permit aspirationof material dislodged by the cutter tip.

In accordance with another aspect of the present invention, a method ofremoving material from a vessel is provided. The first step of themethod is providing an elongate flexible tubular body having a proximalend with a control and a distal end with a rotatable cutter tip. Thedistal end of the elongate body is then advanced transluminally throughthe vessel to the material to be removed. The rotatable cutter tip isthen rotated. Next, portions of the material to be removed are drawn byapplication of a vacuum proximally past the rotatable cutter tip andinto the tubular body. Feedback may be provided to the operator inresponse to changes in the load on the rotatable cutter tip.

In accordance with a further aspect of the present invention, arotatable tip for use in an elongate flexible tubular catheter isprovided for removing material from a vessel. The tip has a tip bodyhaving a proximal end and a distal end and a longitudinal axis ofrotation extending between the two ends. A generally helical thread isprovided on at least a distal portion of the tip body. Also, at leastone radially outwardly extending cutter is provided on a proximalportion of the tip body.

A rotational medical device having an elongate flexible tubular body isprovided in accordance with another aspect of the present invention. Thetubular body has a proximal end and a distal end. A rotatable element iscontained within and projecting distally from the flexible tubular bodysuch that the rotatable element is either in sliding contact with or isspaced radially inward from the tubular body. An aspiration lumenextends within the tubular body between the interior surface of a wallof the tubular body and the exterior surface of the rotatable element.At the distal end of the tubular body, the present invention provides arotatable tip which is connected to the rotatable element. The presentinvention also provides a control at the proximal end of the tubularbody. The tubular body has a first cross-sectional area and theaspiration lumen has a second cross-sectional area wherein thecross-sectional area of the aspiration lumen is at least about 30% andpreferably is as much as 50% or more of the cross-sectional area of thetubular body.

Preferably, a guidewire lumen extends throughout the length of thetubular body, or through at least a distal portion of the tubular body.The catheter may be used with either a conventional closed tipguidewire, or with a hollow guidewire having a distal opening thereonsuch as for infusion of therapeutic drugs, contrast media or otherinfusable material.

In accordance with another aspect of the present invention, a method ofremoving material from a patient is also provided. An elongate flexibletubular body, having a proximal end and a distal end, is provided. Thetubular body has a rotatable tip on the distal end and a control on theproximal end. The rotatable tip is advanced to the location of thematerial to be removed. The control is manipulated to activate a vacuumthrough the tubular body. Then the control is manipulated to commence arotation of the rotatable tip to remove the material from the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the device of the present invention;

FIG. 2 is a cross-sectional side elevational view of the distal tip ofthe device of FIG. 1, showing an embodiment of the cutter assembly;

FIG. 3 is a side elevational view of the cutter tip of FIG. 2;

FIG. 4 is an end view taken along the line 4--4 of the cutter tip ofFIG. 3;

FIG. 5A is a cross-sectional side elevational view of a secondembodiment of the cutter tip and housing;

FIG. 5B is a cross-sectional view of the cutter tip and housing takenalong the lines 5B--5B of FIG. 5A;

FIG. 6 is a side elevational cross-section of a control in accordancewith one embodiment of the invention;

FIG. 7A is a schematic illustration of a pinch-valve switch in a closedposition;

FIG. 7B is a schematic illustration of a pinch-valve switch in an openposition.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, an illustrative embodiment of the inventivesurgical instrument 10 is shown. In general, the surgical instrument 10comprises an elongate flexible tubular body 12 having a proximal end 14and a distal end 16. A control 18 is provided on the proximal end 14 ofthe tubular body 12 for permitting manipulation of the instrument 10.The control 18 carries electronic controls and indicators as well asvacuum controls as will be discussed below.

Referring to FIG. 2, the tubular body 12 is provided with an elongatecentral lumen 20 and a cutter housing 21 for rotatably receiving acutter tip 22. Cutter tip 22 is rotationally coupled to the control 18by way of an elongate flexible drive shaft 24. In an over-the-wireembodiment, the drive shaft 24 and cutter tip 22 are provided with anaxially extending central lumen 26 for slidably receiving a guidewire 28as will be understood by those of skill in the art.

The diameter of the guidewire 28 is generally in the range of about0.010 inches to about 0.020 inches. The length of the guidewire 28 maybe varied to correspond to the distance between the percutaneous accesssite and the lesion being operated upon. For example, the guidewire 28should be long enough to allow the cutter tip 22 of the present surgicalinstrument 10 to track along the guidewire 28 and reach the targetocclusion while also allowing a proximal portion of the guidewire toremain exterior to the patient for manipulation by the clinician. In anapplication for removing coronary artery atheroma by way of a femoralartery access, guidewires 28 having lengths from about 120 cm to about160 cm may be used as will be understood by those of skill in art. Forother applications, such as peripheral vascular procedures includingrecanalization of implanted vascular grafts, the length of the guidewire28 will depend upon the location of the graft of other treatment siterelative to the percutaneous puncture. Suitable guidewires 28 forcoronary artery applications include those manufactured by Guidant orCordis.

To accommodate the guidewire 28, as shown in FIGS. 3 and 4, oneembodiment of the present cutter tip 22 includes a generally cylindricalsleeve shaped body 30 having a central lumen 32. The cylindrical body 30of cutter tip 22 generally has an external diameter of between about0.056 inches and 0.092 inches. In one embodiment, the external diameteris approximately 0.042 inches. The body 30 has a wall thickness betweenabout 0.003 and about 0.010 inches. In one embodiment, the wallthickness is about 0.009 inches. The length of one embodiment of thepresent cutter tip 22 is approximately 0.096 inches but the length mayalternatively vary from about 0.040 to about 0.120. In general, tip 22lengths of no more than about 0.100 are preferred; shorter tip lengthspermit greater lateral flexibility and enable remote access as will beapparent to those of skill in the art.

As shown in FIG. 3, the cylindrical body 30 of the present cutter tip 22has a proximal end 34 and a distal end 36. In one embodiment, an end cap38 is provided on the distal end 36 of the present cutter tip 22. Theend cap 38 is preferably disk shaped to correspond to the cylindricalbody 30 of the present cutter tip 22. The end cap 38 has a thickness ofapproximately 0.007 inches. However, the end cap 38 thickness may rangefrom 0.003 to 0.020. The end cap 38 has an outside diameter whichcorresponds to the outside diameter of the distal end 26 of the presentcutter tip 22. End cap 38 has a centrally located aperture 39. Theaperture 39 preferably has a diameter of between about 0.017 and about0.025. In one embodiment, the aperture 39 has a diameter ofapproximately 0.022 inches. Additionally, the outside distal edge of theend cap 38 is desirably rounded such that the sharp machined edge isremoved. Alternatively, the end cap 38 may be a unitary portion of thepresent cutter tip 22.

A connector portion 40 is provided on the proximal end 34 of the presentcutter tip 22 for rotatably interlocking the cutter tip 22 within thecutter housing 21. The connector portion 40 may take various forms aswill be appreciated by one skilled in the art. In the embodiment shownin FIGS. 3 and 4, the connector 40 comprises two radially outwardlyextending supports such as wedge-shaped cutter blocks 42. The cutterblocks 42 may be formed by removing material from an annular flange atthe proximal end 34 of the cutter tip 22.

Although two opposing cutter blocks 42 are illustrated in FIGS. 3 and 4,three or four or more cutters may be utilized as will be apparent tothose of skill in the art. In general, the cutters will becircumferentially evenly distributed about the longitudinal axis of thecutter tip, to improve balance during rotation of the tip. For example,three cutters would preferably extend radially outwardly from thecylindrical wall 30 on 120° centers. Similarly, four radially outwardlyextending cutters would be located on 90° centers.

The illustrated connector 40 has an outside diameter taken through theopposing cutter blocks of approximately 0.071. The outside diameter willgenerally range from about 0.057 to about 0.096. The thickness of thecutter blocks taken in the axial direction is about 0.010 but may rangefrom about 0.004 to about 0.025. In general, the OD through cutterblocks 42 is selected to cooperate with the inside diameter of anannular retaining groove 54 discussed below, to axially retain the tip22 while permitting rotation thereof with respect to the housing 21.

As shown in FIG. 3, the cutter tip 22 also has two axially extendingslots 44 which are formed in the cylindrical wall 30 adjacent eachcutter block 42. The slots 44 are preferably about 0.005 inches inwidth; however the width may range from approximately 0.001 toapproximately 0.025. The slots 44 of the present cutter tip 22 are alsoat least about 0.025 in length along the longitudinal axis of the body30. One skilled in the art will readily appreciate that the slots 44 ofthe present cutter tip 22 can be varied in axial length to vary theradially outwardly directed force on the cutter block 42. The slots 44allow radial inward compression of the connector 40 of the cutter tip 22to allow for ease of assembly of the cutter tip 22 with the cutterhousing 21 as described below.

As shown in FIGS. 2-4, an external helical thread 46 extends along aportion of the exterior surface of the cylindrical body 30 of thepresent cutter tip 22. The thread 46 preferably extends from a locationon the cylindrical body 30 which is distal to the connector 40. In oneembodiment having a cutter housing 21 with an inside diameter of about0.0685, the major diameter of the thread 46 is approximately 0.0681inches. However, the major diameter of the present thread 46 may rangefrom about 0.050 to about 0.130 or otherwise, depending upon theintended clinical application. The helical thread 46 of the foregoingembodiment has a pitch of approximately 0.0304 inches. The pitch mayrange from about 0.005 to about 0.060, and may be constant or variablealong the axial length of the cutter tip 22. The thickness of thepresent thread 46 in the axial direction is approximately 0.008 inches;however, the thickness may range from about 0.003 to about 0.05, and maybe constant or variable along the length of the thread 46.

In the embodiment illustrated in FIG. 2, the outside diameter of thethread 46 has a close sliding fit with the inside diameter of the cutterhousing 21. In this configuration, the atheromatous material will be cutby the helical threads and assisted by the cutter blocks 42. However, itmay be desirable in some embodiments to provide an annular space betweenthe outside diameter of the thread 46 and the inside diameter of thecutter housing 21. By spacing the thread 46 radially inwardly from theinside wall of the central lumen, an annular space is provided formaterial to pass through the cutter without being severed by the thread46. This may be utilized in conjunction with the vacuum, discussedbelow, to aspirate material into the atherectomy device without thenecessity of complete cutting by the thread 46. This may be advantageousif the aspiration rate is desirably set higher than the rate which wouldoccur if otherwise limited by the thread 46. In addition, certain lesionmorphologies, such as those including portions of calcified plaque, maybe more readily aspirated by the rotational atherectomy device if thethread 46 is not required to cut all the way through the aspiratedmaterial. In general, the radial distance between the thread 46 and theinside wall of the cutter housing 21 will be within the range of fromabout 0.0001 to about 0.008, to be optimized in view of the desiredperformance characteristics of the particular embodiment. In anembodiment intended solely to aspirate soft atheromas, the thread 46 maybe deleted entirely, so that cutting occurs by the cutting blocks 42 incooperation with the aspiration provided by the vacuum source.

As shown in FIGS. 2 and 3, the illustrated thread 46 makes approximatelytwo turns about the cylindrical body 30; however, one skilled in the artwill readily appreciate that the thread 46 may make as few as about 0.25and as many as about 10 turns about the cylindrical body 30 of thecutter tip 22. In addition, while the present cutter tip 22 isillustrated and described as having a single thread, one skilled in theart will appreciate that the cutter tip 22 may also have multiplethreads, a discontinuous thread or no threads. For example, a series ofradially outwardly extending blades or posts arranged in a helicalpattern around the tubular body can be provided. As shown in FIG. 3, thedistal portion of the thread 46 advantageously has its leading edgerounded or broken to remove the sharp corner. By eliminating the sharpedge, the risk of accidental damage to the patient is reduced. Thedistal edge of the cylindrical body 30 and cutter blocks 42 may also bechamfered to eliminate sharp edges.

One embodiment of the cutter tip 22 is rotatably retained in a firstembodiment of a cutter housing 21. The illustrated housing 21 isexternally a double step cylinder having a proximal end 50 and a distalend 52 as shown in FIG. 2. The distal exterior diameter is approximately0.0790 inches; however, the distal exterior diameter may range fromabout 0.039 to about 0.150 depending upon cutter tip design and theintended clinical application. The distal section 53 in the illustratedembodiment is about 0.117 inches in length but the length may vary fromabout 0.020 to about 0.50. The outside diameter of the proximal sectionmay be less than the diameter of the distal section to produce anannular shoulder 51 to limit concentric proximal advance of the proximalsection within the tubular body 12. The proximal section extends axiallyfor approximately 0.09 inches but it may vary as will be understood bythose of skill in the art.

In general, the cutter housing 21 may be secured to the distal end ofthe tubular body 12 in accordance with any of a variety of techniqueswhich will be known to those of skill in the art. The concentricoverlapping joint illustrated in FIG. 2 can be utilized with any of avariety of secondary retention techniques, such as soldering, the use ofadhesives, solvent or thermal bonding. Alternatively, or in conjunctionwith any of the foregoing, an outer tubular sleeve may be heat shrunkover the joint between the cutter housing 21 and the tubular body 12.

The interior configuration of the present cutter housing 21 isprincipally a stepped cylinder as shown in FIG. 2. The distal internaldiameter is approximately 0.0689 inches and may range from about 0.050to about 0.150. The proximal end of the present cutter housing has aninternal diameter of approximately 0.0558. The internal diameter canalternatively range from about 0.035 to about 0.130.

At the proximal end of the distal step is a shallow radially outwardlyextending retaining groove 54. The retaining groove 54 is approximately0.0015 deep relative to the distal section and may range in depth fromabout 0.0005 to about 0.020. The retaining groove 54 in the illustratedembodiment is about 0.0135 in axial width; however, as one skilled inthe art will readily appreciate, the groove width may be varied andstill accomplish its retention function.

As illustrated in FIG. 2, the retaining groove 54 cooperates with thecutter blocks 42 of the present cutter tip 22 to retain the cutter tip22 within the cutter housing 21. The cutter blocks 42 provide a bearingsurface for the cutter tip 22 to facilitate the rotational movement. Inaddition, due to the cooperative engagement between the cutter blocks 42and the retaining groove 54, the cutter tip 22 is substantiallyrestrained from axial movement within the cutter housing 21.

As shown in FIG. 2, the distal end 36 of the illustrated cutter tip 22is approximately axially aligned with the distal end 52 of the cutterhousing 21. As such, the length of the cutter housing 21 distal of theretaining groove 54 corresponds to the length of the cutter tip 22 whichextends distally from connector 40. By creating a substantially flushsurface at the distal end 52 of the cutter housing 21 and cutter tip 22,the possibility of accidental damage to the intima from the cutter tip22 is reduced. One skilled in the art will readily recognize, however,that the distal end 36 of the cutter tip 22 may alternatively extendbeyond, or be recessed within, the distal end 52 of the cutter housing21.

A second embodiment of the cutter tip 60 and associated cutter housing70 are illustrated in FIGS. 5A and 5B. The second embodiment of thecutter tip 60 is principally a radially symmetrical structure such as acylindrical body 61 having an annular retention structure such as aretaining groove 62 located near the proximal end 64. The retaininggroove 62 in the illustrated embodiment is about 0.007 deep, and about0.008 wide, although both can be varied as may be desired. Proximal tothe retaining groove 62, the outside diameter of the cylindrical bodytapers from about 0.04 to about 0.036. Preferably, all edges are brokenor chamfered to ensure burr free corners and facilitate assembly. Thesecond embodiment of the cutter tip 60 also has a generally helicalthread 66 similar to that of the first embodiment.

The second embodiment of the cutter tip 60 is snap fit within a secondembodiment of the cutter housing 70. The second embodiment of the cutterhousing 70 is similar to the first embodiment with the exception thatthe retaining groove of the first housing is replaced by a set ofradially inwardly extending retaining members 72. As shown in FIG. 5B,the present cutter housing 70 has three retaining members 72, preferablycircumferentially symmetrically distributed (i.e. on 120° centers). Oneskilled in the art will recognize that the number, size and shape of theretaining members can vary. At least two will generally be used toachieve opposition, and embodiments having 3, 4, 5 or more may bereadily produced.

The retaining members 72 serve the added function of stationary cutterblocks in the second embodiment. As such the retaining members 72 shouldbe sized accordingly. The illustrated retaining members 72 are about0.007 inches thick in the axial direction; however, one skilled in theart will appreciate that the thickness can range from about 0.003 toabout 0.030 or otherwise depending upon material choice and the desireddegree of axial restraint. The retaining members 72 extend about 0.007inches inward from the interior wall of the cylindrical cutter housing70. The retaining member 72 length can vary, however, depending upon thedesired dimensions of the cutter housing and tip body. As shown in FIG.5B, the side edges 73 of the retaining members 72 may be provided with aradius such that the radial interior and exterior ends are wider thanthe central portion.

As one skilled in the art will appreciate, the retaining members 72 areprovided to engage within the retaining groove 62 of the cutter tip 60such that the cutter tip 60 is substantially restrained from axialmovement relative to the cutter housing 70. The retaining members 72also provide a bearing surface for the rotational movement of the cuttertip 60 relative to the cutter housing 70. Similar to the firstembodiment, the distal end 65 of the cutter tip 60 is approximatelyflush with the distal end 74 of the cutter housing 70. Alternatively,the distal end 65 of the cutter tip 60 can be slightly recessed withinthe distal end 74 of the cutter housing 70 by as much or more than isshown in FIG. 5A.

As indicated in FIG. 2, the distal end of a flexible drive 24 is firmlysecured within the axial bore 27 of the cutter tip 22. The cutter tip 22is secured to the flexible drive 24 by any of a variety of ways such ascrimping, soldering, interference fit structures, and/or threadedengagement as will be apparent to those of skill in the art.Alternatively, the flexible drive 24 could extend axially through thecutter tip 22 and be secured at the distal end 36 of the cutter tip.

The flexible drive 24 is preferably a hollow, laminated flexible "torquetube" such as may be fabricated from an inner thin-wall polymerictubing, an intermediate layer of braided or woven wire, and an outerpolymeric layer. In one embodiment, the torque tube comprises apolyimide tube having a wall thickness of about 0.004 inches, with alayer of braided 0.0015 inch stainless steel wire embedded therein.

The laminated construction produces a tube with a very high torsionalstiffness and surprising tensile strength, but which is reasonablyflexible with respect to the longitudinal axis. However, depending uponthe desired torque transmission, diameter and flexibility, any of avariety of other materials and constructions can also be used. Ingeneral, the drive tube must have sufficient torsional rigidity to drivethe cutter tip through reasonably foreseeable blockages.

The outside diameter of one embodiment of the present hollow flexibledrive tube is approximately 0.032 inches, but can range between about0.020 inches and about 0.034 inches or more. One skilled in the art willappreciate that the diameter of the flexible drive tube 24 is limited bythe minimum torsional strength and guidewire diameter at the low end,and maximum permissible catheter outside diameter at the high end.

The selection of a hollow drive tube allows the device to be advancedover a conventional spring-tipped guidewire, and preferably still leavesroom for saline solution, drugs or contrast media to flow through thelumen of the drive tube and out of the distal opening on the cutter tip.The internal diameter of the present hollow flexible drive tube is thuspartially dependent upon the diameter of the guidewire 28 over which theflexible drive tube 24 must track. The internal diameter of theguidewire lumen in one embodiment of the present hollow flexible drivetube intended for use with a 0.018 inch diameter guidewire, for example,is approximately 0.024 inches. Because the flexible drive tube 24extends between the control 18 and the cutter tip 22, the length of thepresent hollow flexible drive tube 24 must be sufficient to allow thecutter assembly to reach the target occlusion while also allowingadequate space outside of the patient for the operator to manipulate theinstrument.

The lumen 20 of the assembled device is thus an annular space definedbetween the inside wall of the flexible tubular body 12 and the outsideof the flexible drive tube 24. This lumen 20 is used to aspirate fluidand material from the cutter. Preferably, sufficient clearance ismaintained between the tubular body 12 and the rotating drive tube 24 tominimize the likelihood of binding or clogging by material aspiratedfrom the treatment site.

In general, the cross-sectional area of the lumen 20 is preferablymaximized as a percentage of the outside diameter of the tubular body12. This permits an optimization of maintaining a minimal outsidediameter for tubular body 12, while at the same time permitting anacceptable flow rate of material through the aspiration lumen 20, withminimal likelihood of clogging or binding which would interrupt theprocedure. Cross-sectional area of the aspiration lumen 20 is thusoptimized, if the drive tube is constructed to have relatively hightorque transmission per unit wall thickness such as in the constructionsdescribed below. In one embodiment of the invention, intended forcoronary artery applications, the outside diameter of tubular body 12 isabout 0.080. The wall thickness of tubular body 12 is about 0.008, andthe outside diameter of torque tube 24 is about 0.031. This produces across-sectional area of the available portion of central lumen 20 ofabout 0.00245 square inches. This is 50% of the total cross-sectionalarea of the tubular body 12. Preferably, the cross-sectional area of thelumen 20 is at least about 25%, more preferably at least about 40%, andoptimally at least about 60% of the total cross-sectional area of thetubular body 12.

The tubular body 12 may comprise any of a variety of constructions, suchas a multilayer torque tube. Alternatively, any of a variety ofconventional catheter shaft materials such as stainless steel, or singlelayer polymeric extrusions of polyethylenes, polyethylene terephthalate,nylon and others well known in the art can be used.

In one embodiment, for example, the tubular body 12 is a PEBAX extrusionhaving an outside diameter of approximately 0.090 inches. However, theouter diameter can vary between about 0.056 for coronary vascularapplications and about 0.150 for peripheral vascular applications. Also,because the tubular body 12 must resist collapse under reasonablyanticipated vacuum forces, the foregoing tubular body 12 has a wallthickness of at least about 0.005 inches. The wall thickness can,however, be varied depending upon materials and design.

The distal end of the tubular body 12 is affixed to the proximal end 50of the cutter housing 22 as shown in FIG. 2. The proximal end of thetubular body 12 is affixed to the control 18 as described below.

A reinforcing tube 80 extends from the control 18 unit along a proximalportion of the tubular body 12. The reinforcing tube provides support toavoid over bending and kinking at the proximal end of the drive tube 24.The point at which the flexible drive tube 24 is rigidly connected tothe control 18 is a likely point of damaging bending forces. As such,the reinforcing tube 80 is provided to reduce the likelihood of afailure at that location due to bending forces. The reinforcing tube 80extends distally over the tubular body 12 at least about 3 cm andpreferably about 6 cm, and comprises silicone or other conventionalbiocompatible polymeric material. As shown in FIG. 6, the reinforcingtube 80 is fastened to the control 18 such as by interference fit over asnap tip assembly 82 through which the flexible drive tube 24 andtubular body 12 enter the control 18. Thus, the reinforcing tube 80envelopes a proximal portion of the tubular body 12.

The flexible drive tube 24 and tubular body 12 operatively connect thecutter tip 22 and cutter housing 21 to the control 18. The tubular body12 and drive tube 24 enter the control 18 through the snap tip assembly82 as shown FIG. 6. The snap tip assembly 82 is provided with aconnector such as a hub 84 having a central lumen in communication witha vacuum manifold 86. The tubular body 12 is connected to the hub 84.The hub 84 is rotatable, and enables the user to rotate the tubular body12 relative to the control 18.

The tubular body 12 may be reinforced internally where it passes throughthe hub 84 by a thin-wall stainless steel tube (not shown) that extendsthrough and is bonded to the hub 84. Since it is difficult to bond toacetal, in the case of a white acetal (Delrin) hub, for example, aportion of the injection-molded hub 84 bore can be hexagonal or othernon circular cross-sectional shape. Epoxy adhesive (not shown) injectedinto this space around the stainless steel tube acts like a spline,preventing the tube from rotating in the hub or pulling back out.

The acetal hub 84 bonded to the proximal end of the tubular body 12provides a means of rotating the snap tip assembly 82 relative to thecontrol 18. Friction to limit this rotation is provided by the face of agrommet 87 compressed against the proximal perimeter flange of the hub.Acetal (Delrin) may be used for the hub 84 to provide long-term memoryof the snap-fit tabs that secure this part to the rest of the assembly.The hub 84 snaps onto and seals with the vacuum manifold 86.

As best seen in FIG. 6, an injection molded acrylic vacuum manifold 86is fastened to a vacuum hose 88 at one outlet and to a motor 90 at asecond outlet. The hub-end of the vacuum manifold 86 houses two siliconerubber O-rings 85 that function as dynamic (rotatable) seals between themanifold walls and the tube. The opposite end of the manifold, where theproximal end of the drive tube 24 is visible, contains a pair of butylrubber fluid seals 104. The two vacuum manifold fluid seals 104 aremounted back-to-back, with the lips pointing away from each other. Inthis configuration, the innermost seal protects against positivepressure leaks such as blood pressure and the outer-facing seal excludesair when the system is evacuated. These dynamic seals may be lubricatedwith silicone grease.

The vacuum manifold 86 is connected to a motor 90 through use of athreaded motor face plate 100. The vacuum manifold 86 is threaded ontothe face plate 100. The face plate 100 is attached to the output end ofthe motor 90 by a threaded fastener 102. The present motor 90 is amodified 6-volt D.C. hollow-shaft, 22 mm O.D. motor built by MicroMo,regulating both speed and torque as required as discussed below.

Power is transmitted from the motor 90 to the drive tube 24 by adhesivebonding a length of medium-wall stainless steel tubing, such ashypodermic needle stock measuring 0.036" I.D.×0.053" O.D. beforecoating, around the driven proximal end of the drive tube 24. This rigidtube, called the drive shaft, is a concentric slip fit through the0.058" I.D. of the hollow motor shaft, and extends beyond the length ofthe motor shaft in both directions. The drive shaft is coated on theouter surface with 0.001" of Type-S Teflon. The Teflon-coated, exposedends of the drive shaft provide a smooth wear-surface for the dynamicfluid seals.

A small drive plate 103, bonded to the rear end of the drive shaft 107,mates with a drive sleeve 105 permanently attached to the 0.078" O.D.motor shaft 92. Together, the drive plate 103 and sleeve 105 form aconcentric drive coupling between the motor shaft 92 and the drive shaft107, which in turn is bonded to the drive tube 24. The splinedconfiguration of the drive coupler allows approximately 1/4" of relativelongitudinal movement between the plate 103 and sleeve 105, sufficientto accommodate thermal and mechanical changes in the relative lengths ofthe outer tube 12 and flexible drive tube 24. An integral flange on thedrive sleeve 105 serves as a slinger to deflect fluid away from the rearmotor bearings in the event of a leaking fluid seal.

The drive sleeve 105 and drive plate 103 are preferably molded fromPlexiglas-DR, a medical-grade, toughened acrylic resin made by Rohm andHaas. These parts have shown little tendency to crack in the presence ofthe chemicals that might be present or used in the assembly of thedevice; these chemicals include cyanoacrylate adhesives andaccelerators, motor bearing lubricants, alcohol, epoxies, etc. The drivesleeve 105 and drive plate 103 are lightly press-fitted to theirrespective shafts 92, 107, and secured with a fillet of adhesive appliedto the outside of the joints.

To the right of the motor 90 in FIG. 6 is an infusion manifold 108. Thisis designed exclusively as an input circuit; theoretically any fluidthat can be pumped or injected at a pressure exceeding the diastolicpressure in the artery or vein could be used, but saline solutions,therapeutic drugs and fluoroscope contrast media are the ones mostlikely to be used with this device. Saline solutions are needed to purgeair from the tubular body 12 before the procedure to prevent airembolism, and may also be used during the atherectomy procedure toprovide a continuous flow of liquid (other than blood) during cutting tohelp carry debris through a return circuit. In this case, an elevatedI.V. bag may be used to ensure a continuous, low-pressure flow throughthe system.

At various times during the procedure, the surgeon may request that abolus of contrast medium be injected to enhance the fluoroscopic imageof the artery or vein, either to position or direct the guide wire,locate the blockage, or to confirm that the stenosis has indeed beenreduced. Contrast medium is a relatively dense material and highpressure (several atmosphere) is usually required to force the materialquickly through a small, elongated lumen 26 of the drive tube 24.

In the case of the present surgical instrument, the infusion manifold108 is comprised of several components. The first component is aninfusion port which may contain a medical infusion valve 109 such asthat supplied by Halkey-Roberts Corp. This silicone rubber check valveassembly is designed to be opened by insertion of a male Luer-taper (orlock) fitting. The valve stays open as long as the taper fitting remainsin place, but closes immediately if it is withdrawn. This actionprovides simple access when needed, but provides the required backflowprevention to minimize loss of blood through this route. The infusionvalve 109 is permanently bonded into the side arm of the flush portmanifold 111, an injection-molded, transparent acrylic fitting.

The flush port manifold 111 has an integral threaded extension thatprotrudes from the right-hand side of the control 18. The threadedextension is provided with a silicone guide wire seal 113, and an acetal(Delrin) guide wire clamp nut 112 that together function as a hemostasisvalve compression-fitting. The guide wire 28 extends through both theseal and the nut 112.

With the clamp nut 112 screwed in or tightened, the silicone guide wireseal 113 compresses against the guide wire 28, locking it in place, andpreventing leakage of blood or air. When it is necessary to slide theguide wire 28 or to slide the surgical instrument 10 along the guidewire 28, the clamp nut 112 must be loosened to reduce the clampingaction somewhat. If no guide wire 28 is used, the seal 113 compressesagainst itself and closes off the passageways to leakage. Delrin may beused for the clamp nut 112 to minimize stiction and galling of thethreads during use. An internal shoulder on the threaded portion of thenut acts as a position stop, preventing extrusion of the seal 113 thatmight otherwise result from over-tightening.

A fluid channel extends up the center of the flush port manifold 111,continuing through the open lumen of the drive tube 24, all the way outthrough a distal aperture 39 in the tip of the helical cutter tip 22.The guide wire 28 follows the same path. A leak-proof between the flushport manifold 111 and the drive tube 24 is desirable. Accordingly, amolded acrylic flush port flange 106 is bonded to the motor end of theflush port manifold 111, creating a chamber housing a low durometerbutyl rubber lip seal 114. The tiny rubber part forms an effectivedynamic seal against one end of the Teflon-coated drive shaft 107 bondedaround the end of the drive tube 24. Lip seals are pressure-compensatingdevices that function at zero or low pressure by light elastomericcompression against a shaft, minimizing the drag component in a dynamicapplication. When pressure against the seal increases, the lip tightensagainst the shaft, increasing both the sealing action and the dynamicfriction. In this application, however, a high pressure sealingrequirement only occurs during injection of contrast medium, typicallywhen the cutter tip 22 is stopped. Lower pressure dynamic sealing isrequired during saline infusion, however, so pressure compensating lipseals are an ideal design solution here. Lip seals are inherentlydirectional devices, sealing in one direction, and pressure-relieving inthe other. Care must be taken to position the fluid seals properly ineach application.

The fluid seal 104 is transfer-molded butyl rubber, with a 0.047"(generally within the range of from about 0.035 to about 0.050 inches)lip I.D., running on a silicone-grease-lubricated, Teflon-coated driveshaft 107 with a 0.055" O.D. The medical-grade silicone grease reducesfriction quite well, but tends to be forced away from the lip duringprolonged use. The Teflon coating on the drive shaft acts as a back-uplubricant that prevents seal damage in the event the grease is lost.Frictional drag is acceptably low with this arrangement, yet sealingappears adequate to prevent leakage during use.

Moving back to the Y-shaped coupling unit 86, a heavy walled siliconerubber vacuum hose 88 is attached to the remaining port of the Y-shapedvacuum manifold 86. The vacuum hose 88 generally extends between theY-shaped coupler 86 of the control 18 and a vacuum source 19 such as thehouse vacuum of the catheter lab of a hospital or a vacuum bottle.

The vacuum hose 88 extends down through a pinch valve switchconfiguration 120 described in detail below. The vacuum hose 88 thenfurther extends to the bottom portion of the control 18. A pinchresistant sleeve 116 is preferably provided to prevent the pinching ofthe vacuum hose 88 as it exits the control 18. Additionally, the pinchresistant sleeve 116 provides a liquid seal to prevent liquids fromentering the control 18 unit during operation.

Returning to the pinch valve switch configuration 120, the pinch valveswitch 120 provides a means to assure that the motor 90 driving therotatable drive shaft 24, which in turn drives the cutter tip 22, is notactivated unless the vacuum is being applied. As such, power from thepower source 122 is provided to the motor through an electronic switch130. The pinch valve switch 120 comprises a push button oriented alongthe Z axis shown in FIG. 7A. The switch push button 124 can translatealong the Z axis when depressed by the user. The lower portion of thepush button is provided with a unshaped cut out forming a tunnel alongthe x-axis. The cut out is sized to correspond to a compression spring126. The present compression spring 126 is a precision-lengthstack-wound button spring fabricated from 0.027" diameter 302 stainlesssteel wire, with a closed retainer loop at one end. The push button 125is located along a portion of the compression spring 126 such that thepush button 124 rests on the compression spring 126 and is supported inan up position. The switch push button 124 thus can travel to a downposition when pressed by the operator as shown in FIG. 7B. Thecompression spring 126 provides a bias such that the push button 124will return to the up position when released.

The switch push button 124 is further provided with an axial arm 128which extends in a direction perpendicular to the direction of travel ofthe push button 124. The electronic switch 130 is located below theaxial arm 128 of the switch push button 124. As the switch push button124 is depressed, contact is made on the electrical switch 130. Theelectrical switch 130 allows current to flow from a power source 122 tothe motor. Thus, depression of the push button 124 creates a flow ofcurrent which drives the motor 90. The motor drives the drive tube 24and cutter tip 22 of the present surgical instrument 10.

Advantageously, the compression spring 126 is attached to a pinchingmember 132 of a pinch valve. As the push button 124 is depressed, thecompression spring 126 is deflected. The deflection in the compressionspring 126 causes the pinch member 132 to retract. Thus, the pinchmember 132 is retracted as soon as the push button 124 depressionbegins. As the pinch member 132 is retracted, a vacuum flow is allow topass through the pinch valve 120. Advantageously, the amount of flowthrough the valve depends on how far the button 124 is depressed, makingit easy to control the amount of suction. Depressing the button furtherto the switch contact makes the vacuum open fully. Thus, depressing thebutton starts the vacuum first and then cutting action is started secondto eliminate the risk of cutting without aspiration. Because repeatedcycles of opening and closing the valve tend to shift the position ofthe tube, internal ribs are preferably provided in the control 18 tohold the tube in the right place.

The return flow path in the lumen 20 of the outer tube 12 outside thedrive tube 24, augmented by suction from an external vacuum source,starts at the cutter tip 22, spirals through the helical thread 46 andthe cutter blocks 42 of the cutter tip 22, through the outer lumen 20 ofthe outer tube 12 to the vacuum manifold 86, and then through a lengthof vacuum tubing 88 to a tissue collection/fluid separation containersuspended from the I.V. Pole. The collection container is connected to avacuum collection canister that may be, in turn, hooked to a regulatedcentral vacuum source or a suction collection pump or vacuum container.Flow through the vacuum manifold 86 is controlled by the pinch valvemechanism 120 integral to the drive module; this is actuated by the samespring-loaded button that starts the drive motor. The current is notallowed to flow to the motor 90 until the push button 124 completes itstravel. Thus, the depression of the push button 124 controls the vacuumsuch that the motor 90 is not energized without the vacuum firstflowing.

The pinch valve assembly is preferably designed with a "lock-out"feature (not shown) that secures the button 124 in a partially depressedposition where the vacuum tube 88 is no longer compressed, but theswitch 130 is not yet actuated. This preserves the elastic memory of thepinch tube and protects the device from accidental actuation duringhandling or storage. In its present form, a thin, flexible lock-out wirewith an identifying tag (not shown) can be inserted at the last stage ofassembly, passing through a hole in the button (not shown) and extendingthrough a notch in the sidewall of the control 18. In thisconfiguration, the highly-visible tag protrudes from the side of thecontrol 18, preventing use of the device until the wire is pulled free.This action releases the button 124 and returns the control 18 to afunctional condition. Once removed from the original locked position,the lock-out wire (not shown) cannot be reinserted without disassemblyof the control 18.

The motor and feedback indicators of the device 10 are controlled byelectronic circuitry 131 such as may be contained on a printed circuitboard 133. The circuitry providing the power to the motor 90 alsoprovides a means for checking the load on the motor. As known to thoseskilled in the art, when a D.C. motor as used in this inventionencounters resistance to rotational movement, an increased load isplaced on the power source 122. Accordingly, the circuitry 131 isprovided with the capability to identify and indicate the speed and/ortorque.

In one embodiment, a motor controller 134 provides the motor 90 with therequired energy by using a combination of missing pulse and pulse widthmodulation. The motor speed is sensed by measuring the backelectromotive force (EMF), which is proportional to speed. A portion ofthe back EMF is fed to the controller 134, which varies the drive powerto the motor 90 to maintain a constant speed. The circuit values of thecontroller 134 allow speed settings of 1,000 to 8,000 RPM. The speedchosen for no load operation in one embodiment is 3,200 RPM. Motortorque is limited to from about 0.10 to about 0.45 oz-inches by sensingthe motor current and reducing the motor drive power to the appropriatelevel.

The power source 122, preferably a 9-volt battery, is not connected tothe controller 134 until the push button 124 is depressed, so there isno standby power drain. In the illustrated embodiment, a green lightemitting diode (LED) is on when the motor is running at normal loads. Ared LED turns on at a motor current of approximately 0.25 amperes,indicating "overload." A switching controller is used for two reasons:(a) it is very efficient--it uses less than 0.015 amperes (the motorcurrent would vary from 0.05 to 0.4 amperes, or perhaps more), and (b)it can deliver maximum torque instantly or demand, even at low motorspeeds, so the likelihood of stalling is minimized.

Alternatively, any of a variety of tactile, auditory or visual alarmscan be provided. For instance, the surgical instrument could vibrate orprovide an audible signal when it encounters an overload situation. Thepulses or tones may vary to correspond to any variance in resistance torotation. For example, the pitch may increase with resistance or thespeed of a repeating pulse of sound may increase. Additionally, where a(CRT) monitor is used to visualize the operation, a visual signal couldbe sent to the monitor to display the operating characteristics of thesurgical equipment. As will be further recognized to those skilled inthe art, other variations of alerting the operator to the operatingcharacteristics of the present invention may be provided.

The present invention thus provides feedback to the clinician in realtime during the progress of the rotational atherectomy procedure. Realtime feedback can allow the clinician to adjust the procedure inresponse to circumstances which may vary from lesion to lesion, therebyenhancing the overall efficiency of the procedure and possiblyminimizing additional risks such as the creation of emboli. Pressing thecutter tip 22 into a lesion with too much force will produce anincreased load, which can then be detected by the circuitry 131 andcommunicated to the clinician in any of a variety of ways as has beendiscussed. This will allow the clinician to ease back on the distaladvancement force and/or adjust the vacuum or RPM of the cutter tip 22until the load is reduced to an acceptable level, and continue with theprocedure.

In addition, increased load can be incurred by kinking along the lengthof the catheter shaft, thereby reducing the motor speed. Kinkingoriginated loading will be reflected in the feedback mechanism to theclinician, so that the clinician can assess what corrective action totake.

In use, a guidewire 28 is first percutaneously introduced andtransluminally advanced in accordance with well known techniques to theobstruction to be cleared. The surgical instrument 10 is then introducedby placing the cutter tip 22 on the guidewire 28, and advancing thecutter tip along the guidewire 28 through the vessel to the treatmentsite. When the cutter tip 22 has been maneuvered into the correctposition adjacent the proximal terminus of material to be removed, thedrive tube is rotated relative to the tubular body 12 to cause thecutter tip 22 to rotate in a direction which will cause the forward endof the thread 46 to draw material into the housing 21. A circularcutting action is provided by mutual cooperation of the outer cuttingedge of the screw thread 46 with the sleeve of the cutter housing 21 andthe internal peripheral wall of the cutter housing 21. In addition, thecutter housing 21 in cooperation with the cutter blocks 42, effectivelybreaks the strands of material being drawn into the cutter housing 21.The cut material is then carried proximally through the annularpassageway between the flexible drive tube 24 and the tubular body 12under the force of vacuum. If an increase in load and/or decrease in RPMis defected, the clinician can take reactive measures as describedabove. The vacuum then pulls the cuttings through the entire length ofthe lumen 20 and vacuum tube 88 and into a suitable disposal receptacle.The vacuum source may be regulated by a manual or automatic regulatorsuch that a constant flow velocity may be maintained, or blockagesreduced or cleared, through the vacuum tube 88 regardless of theviscosity of the material passing through the vacuum tube 88.

Although this invention has been described in terms of certain preferredembodiments, other embodiments apparent to those of ordinary skill inthe art are also within the scope of this invention. Accordingly, thescope of this invention is intended to be defined only by the claimsthat follow.

What is claimed is:
 1. A rotational medical device comprising:anelongate flexible tubular body, having a proximal end and a distal end;a rotatable element extending through the body; a rotatable tip at thedistal end of the body and connected to the rotatable element; a controlon the proximal end of the body: an indicator in electricalcommunication with the control, for indicating resistance to rotation ofeither the rotatable element or rotatable tip; and an annular spacebetween the rotatable tip and an interior wall of the tubular body.
 2. Arotational medical device as in claim 1, wherein the indicator comprisesa source of tactile feedback.
 3. A rotational medical device as in claim1, wherein the indicator comprises at least one light.
 4. A rotationalmedical device as in claim 1, wherein the rotatable tip comprises agenerally helical flange.
 5. A rotational medical device as in claim 1,wherein the rotational tip is positioned inside of the tubular body. 6.A rotational medical device as in claim 1, wherein the rotatable tip isspaced radially inwardly from the interior wall of the tubular body by adistance within the range of from about 0.0001 to about 0.008 inches. 7.A rotational medical device as in claim 1, further comprising a threadon the rotatable tip.
 8. A rotational medical device as in claim 7,wherein the thread extends between about 0.25 turns and about 10 turnsaround the rotatable tip.
 9. A rotational medical device as in claim 8,wherein the thread is discontinuous.
 10. A rotational medical device asin claim 7, wherein the rotatable tip has an axial length within therange of from about 0.040 inches to about 0.120 inches.
 11. A rotationalmedical device as in claim 7, wherein the thread comprises a pitchwithin the range of from about 0.005 to about 0.060.
 12. A rotationalmedical device as in claim 7, wherein the distal end of the rotatabletip is approximately axially aligned with the distal end of the tubularbody.
 13. A rotational medical device as in claim 7, wherein the distalend of the rotatable tip extends beyond the distal end of the tubularbody.
 14. A rotational medical device as in claim 7, wherein therotatable tip is recessed within the tubular body.
 15. A rotationalmedical device as in claim 1, further comprising at least two radiallyoutwardly extending cutter blocks on the rotatable tip.
 16. A rotationalmedical device as in claim 15, further comprising an annular retaininggroove in the tubular body, for receiving the cutter blocks.
 17. Arotational medical device as in claim 1, wherein the rotatable elementcomprises a torque tube.
 18. A rotational medical device as in claim 17,wherein the torque tube comprises a layer of braided wire.
 19. Arotational medical device as in claim 17, comprising a central guidewirelumen extending throughout the length of the rotational medical device.20. A rotational medical device as in claim 1, wherein the rotatable tipfurther comprises a radially inwardly extending annular recess.
 21. Arotational medical device as in claim 20, wherein the tubular bodyfurther comprises a plurality of radially inwardly extending retainingmembers for rotatably engaging the annular recess.
 22. A method ofremoving material from a vessel, comprising the steps of:providing anelongate, flexible, tubular body, having a proximal end and a distalend, a rotatable tip at the distal end of the tubular body, and acontrol on the proximal end of the tubular body; advancing the distalend of the tubular body transluminally to the material; rotating therotatable tip; drawing portions of the material proximally past therotatable tip and into the tubular body; and providing feedback to theoperator in response to changes in the load on the rotatable tip.
 23. Amethod as in claim 22, wherein the drawing step is accomplished byconnecting a vacuum source to the proximal end of the tubular body. 24.A method as in claim 23, wherein the advancing step comprises advancingthe tubular body along a guidewire.
 25. A method as in claim 23, whereinthe advancing step comprises advancing the tubular body through apercutaneous access device.
 26. A method as in claim 23, furthercomprising the step of infusing fluid through a flush port on theproximal end of the tubular body.
 27. A method as in claim 22, whereinthe advancing step is accomplished by applying axial distal pressure onthe tubular body, and further comprising the step of reducing the amountof axial distal pressure in response to feedback indicating a change inthe load on the rotatable tip.
 28. A method as in claim 23, wherein thecontrol both activates the vacuum and commences rotation of therotatable tip.
 29. A method of removing material from a patientcomprising:providing an elongate flexible tubular body, having aproximal end and a distal end, a rotatable tip on the distal end of thetubular body, and a control on the proximal end of the tubular body;advancing the distal tip of the tubular body to the material to beremoved; manipulating the control to activate a vacuum through thetubular body; and manipulating the control to commence rotation of therotatable tip to remove material from the patient; and infusing fluidthrough a guidewire flush port on the proximal control.
 30. A rotationalmedical device comprising:an elongate flexible tubular body, having aproximal end and a distal end; a rotatable element extending through thebody; a rotatable tip at the distal end of the body and connected to therotatable element; a control on the proximal end of the body; aguidewire lumen extending through the rotatable element; and an axiallyextending aspiration channel between the rotatable element and thetubular body.
 31. A rotational medical device comprising:an elongateflexible tubular body, having a proximal end and a distal end; arotatable element extending through the body; a rotatable tip at thedistal end of the body and connected to the rotatable element; a controlon the proximal end of the body; a guidewire lumen extending through therotatable element; the control being mounted on a handle configured forone hand operation of the rotational medical device, and the controlcapable of activating both rotation of the rotatable tip and applicationof the vacuum.
 32. A rotational medical device as in claim 31, whereinthe control is activateable by single finger operation, and, uponactuation thereof, initiates the application of vacuum within thetubular body before initiating rotation of the rotatable tip.
 33. Arotational medical device as in claim 31, wherein the handle furthercomprises an infusion port, and a proximal guidewire port.
 34. A methodof removing material from a patient comprising:providing an elongateflexible tubular body, having a proximal end and a distal end, arotatable tip on the distal end of the tubular body, and a control onthe proximal end of the tubular body; advancing the distal tip of thetubular body to the material to be removed; manipulating the control toactivate a vacuum through the tubular body; and manipulating the controlto commence rotation of the rotatable tip to remove material from thepatient, wherein rotation of the tip can only be accomplished if thevacuum is on.